1. Field of the Invention
The present invention relates to an information collecting apparatus and an information collecting/analyzing system for measuring signals from various parts and performing logic analysis and the like in order to develop, debug and maintain electronic circuits in various types of electronic machines and the like.
2. Description of the Related Art
In the prior art, this type of logic analyzer, by inputting digital signals corresponding to various parts of an electronic circuit to be measured as logic signals, reads these logic signals at set trigger points, stores them in memory, and after measuring is complete, reads out the logic signals stored in memory and displays various images on a display unit based on the read out logic signals.
A high speed volatile memory is used as a memory for storing the logic signals. Since this high speed volatile memory is relatively expensive, the capacity of the memory mounted in the logic analyzer is somewhat limited.
Consequently, although a high speed logic signal of, for example, 100 MHz or more can be acquired, long term measurement, i.e. reading a large amount of logic signal data, is difficult due to limited memory capacity. As a result, by utilizing the trigger function as described above, short term logic signals are read at required timings and stored in memory.
Meanwhile, there are also applications in which medium to low speed signals of, for example, 1 MHz or less are required to be measured over long periods of one minute or more. In such cases, in order to measure a 16-channel logic signal over 10 minutes at a sampling frequency of 1 MHz, for example, and to read and store the logic signal in memory, a memory capacity of 1.2 GB is required. Although it is possible to realize such a large memory capacity, the cost of memory increases significantly, therefore logic analyzers in which this type of large capacity memory is installed have not been marketed.
Also, in Japanese Patent Application Laid-open Pub. No. Hei 4-194688, for example, a logic analyzer that is provided with an external memory device in place of the above-described memory is disclosed. However, since the external memory device has the same function as the above-described memory and is dedicated to the relevant logic analyzer, there is no significant difference between it and the above-described memory.
In recent years, logic analyzer devices without display units have been marketed on the premise of being used in connection with a host computer such as a personal computer or the like.
Such logic analyzer devices are constructed as shown in the example of FIG. 2.
That is, in FIG. 2, the logic analyzer device 1 is connected to a personal computer 2, thereby forming overall a logic analyzer system.
The logic analyzer device 1 comprises an input unit 3, a storage device 4, a transfer unit 5 and a control unit 6.
The input unit 3 is supplied with a logic signal acquired by probes (not shown) from various parts of an object to be measured 7, in this case an electronic machine, and after the logic signal is shaped by level conversion or the like, it is sampled at a set sampling frequency and output to the storage device 4.
The storage device 4 is constructed from a volatile memory and has a capacity of a maximum of several megabytes, for example, and stores the logic signal input from the input unit 3.
The transfer unit 5 is connected to the personal computer 2 via a communication interface 8, and after measurement by the input unit 3 is complete, reads the logic signal stored in the storage device 4 and sends it to the personal computer 2 via the communication interface 8.
The control unit 6 controls the input unit 3, storage device 4 and transfer unit 5 so that the logic signal is read from the object to be measured 7 at a set trigger timing, stored in the storage device 4, read from the storage device 4 after measurement is completed, and transmitted to the personal computer 2 from the transfer unit 5.
The personal computer 2 includes a transfer unit 2a, a signal processing unit 2b, a storage device 2c, a display unit 2d and a control unit 2e, and forms a logic analyzer system in cooperation with the logic analyzer device 1.
The transfer unit 2a receives a logic signal from the transfer unit 5 of the logic analyzer device 1 via a USB 1.1 specification communication interface 8 or the like, and sends it to the signal processing unit 2b. 
The signal processing unit 2b converts the logic signal from the transfer unit 2a to various types of display signals by storing it in the storage device 2c and performing the appropriate processing based on the logic signal, then outputs the display signals to the display unit 2d. 
In the logic analyzer system using a logic analyzer device 1 and personal computer 2 in this type of structure, digital signals at each portion of the electronic circuit of an object to be measured 7 are input to the input unit 3 of the logic analyzer device 1 as logic signals, whereby the input unit 3 acquires these logic signals at set trigger points and stores them in the storage device 4, and, after measuring is complete, the logic signals stored in the storage device 4 are read out and output to the personal computer 2 from the transfer unit 5 via the communication interface 8.
As a result, the personal computer 2 receives the logic signals transferred from the logic analyzer device 1 by means of the transfer unit 2a, and signal processing is performed by the signal processing unit 2b. The personal computer 2 then stores the data storage processed logic signals in the storage device 2c and outputs various types of display control processed logic signals to the display unit 2d, and various types of displays are executed by the display unit 2d. 
However, in the logic analyzer device 1 and logic analyzer system constructed in this manner, the built-in storage device is restricted from storing measured logic signal data due to its storage capacity in the same way as the logic analyzer device described above, and therefore, performing measurements over long periods is troublesome even when measuring medium to low speed logic signals.
Consequently, when performing measurement of logic signals over very long periods of time, the sampling frequency is greatly reduced, and measurement precision must be sacrificed in order to measure very long periods.
Further, when measuring serial signals of an electronic circuit to be measured, as well as the logical analyzer device, a protocol analyzer must be provided to measure the serial signals, and matching the time axis and standard time of a serial signal measured by the protocol analyzer to a logic signal measured by the logic analyzer device is very difficult.